Effects of binder components and PVA modifier on bonding performance of phosphate binder for sand core-making

A type of heat-curing phosphate binder was proposed, and orthogonal experiments based on the tensile strength of sand samples determined that the optimal composition of the binder was phosphoric acid: water: aluminum hydroxide: magnesium oxide: boric acid = 300: 70: 60: 9: 8. Adding 10% polyvinyl alcohol (PVA) solution during the sand mixture process can significantly improve the 24 h tensile strength of sand samples. When adding 30 g phosphate binder and 8 g 10% PVA solution, the initial tensile strength of the sample is 0.76 MPa, the room temperature tensile strength is 2.29 MPa, and the 24 h tensile strength is 1.73 MPa. The heat-curing modified phosphate sand mold has high tensile strength and low gas generation, which can meet general casting production requirements.